The present invention relates generally to devices and methods for detecting an analyte in a sample. More specifically, the present invention provides devices and methods for rapidly testing a sample for an analyte. Generally, “rapid testing” devices are sample testing devices that rely on the development of a visual and typically non-quantitative signal on the surface of a substrate, such as a membrane. Among rapid tests first used were simple pregnancy tests.
The basic “lateral flow test strip” design is typical now of many tests, including veterinary tests, environmental tests, and clinical diagnostics (disease state) tests. One feature of such tests is that they often can be stored under ambient conditions, and they may not require extensive training in order to run and read them. Such features have made them quite useful for assisting in the diagnoses of diseases like HIV, which affects millions of persons in the developing countries of the world. Rapid testing devices are disclosed in, for example, U.S. Pat. Nos. 5,935,864 and 6,303,081.
Countries lacking an extensive medical infrastructure generally do not have the personnel or the facilities and equipment necessary to collect and process large numbers of clinical samples in a centralized laboratory. Hence, a disproportionate number of individuals (compared to nations with more elaborate medical infrastructures in place) may harbor infections and not know how they are infected. Simplicity, ease of sample collection and use, and protection of the user from exposure to biological fluids are high priorities when developing such a device.
A number of problems arise when clinical diagnostics are being developed. Besides stability issues relating to a product's shelf life (these can be overcome by incorporating appropriate dry chemistries, desiccation of the test, and packaging materials that allow only very low levels of moisture transmission) and especially when diagnostics are being developed for use in places like developing countries, means need to be found that (a) maintain a low overall cost for parts and manufacturing, (b) protect and maintain the integrity of the test strip itself, and (c) combine sample collection within the platform itself, in order to make a test as easy and fool-proof as possible to use.